Electronic testing equipment, such as integrated circuit or board testers, has become more and more complex over the last decades. This is particularly due to the increased functionality of the circuitry to be tested--e.g., latest microprocessors, RISC CPU's, combined logic/memory IC's--, which calls for complex test procedures and highly sophisticated tester equipment.
However, there is also another aspect related to this technology. This is the demand for an integrated tester environment, particularly under production conditions. That is, the integrated test environment does not only include the tester itself, but also supporting machinery, e.g., a prober or handler for automatic supply and exchange of devices to be tested (DUT's, e.g., integrated circuits or loaded or unloaded boards). Further, the handling machinery has to be able to deal with several physical or logical entities, such as lots or cassettes containing DUT's, and process them in the correct order. There are even logical or physical entities which have to be handled by the tester itself (not by additional handling tools); a common example is a wafer containing a multiplicity of integrated circuits (IC's) of the same kind. In the latter case, the contacts of the test head have to be advanced from one die to the next one as soon as the first one has been tested (or the wafer has to be advanced instead), and the correct steps have to be taken when the complete wafer has been tested (e.g., the wafer has to be removed and replaced with the next one).
It will be understood that the sequence of operating steps to be performed is not easy to define. Even worse, they depend completely upon the kind of device to be tested (e.g., board, IC, or wafer), and upon the available equipment (e.g., kind of IC handler). Thus, the manufacturer of a tester cannot provide all of the required control hardware and/or software to a customer; instead, the customer has to adapt the tester himself to his specific demands. On the other hand, once all controllers for a given test equipment have been set up, there is seldom a need for later modifications, just as the available hardware components are not subject to frequent modification or replacement. What may in fact be changed are the test specifications of the IC or the board, but these are widely independent of the environmental specifications.
It will be appreciated that the initial set-up of the control equipment by the customer is a laborious and time-consuming task. The manufacturers of IC or board testers have therefore already tried to meet the customer's demands by the provision of configurable control programs, i.e. control programs which permit adaptation to a specific test environment. However, the control equipment so far known in the art is still difficult and complex to operate. This is mainly due to the fact that the complete sequence of control functions has to be defined without any supporting structure, and that the operator is forced never to lose sight of the overall process, despite of the specific part of the process he is editing. His task can thus still be described as fully-qualified programming, despite the available tools, with all related requirements in terms of time and work.
Yet another drawback of the known control programs is that, once they have been created, they are not easy to modify, due to their complex structure. Further, it is not easy to split the task of making the set-up between multiple operators, just as any of them has to have the "full picture", i.e., knowledge about the overall testing process, and about the work of his colleagues.
Thus, there is a need for a new control processor which avoids the above drawbacks.